It tried to tug the heart strings so hard that they twanged into comedy. Hey, didn't any of these soldiers have kids themselves? Didn't they have brothers, sisters, nephews, nieces? Where did they come from, anyway? Surely most of them would have been rounding up kids in Afghanistan? Actually, I doubt it...
People are programmed to protect kids. You don't overturn that programming by an order from the PM. Really.
Keep it quiet? Tell that to the Iranians!
I suspect it was meant as trying to overturn the old Star Trek ethic, old and new - both "the need of the one can override the need of the many" and "there is no such thing as a no-win situation." Except they had to go and win.
This is RTD's revenge on the fans. Lead them down the garden path with a (totally out of character) love story between Jack and Ianto, bring in all the families, have Gwen get preggers (cripes, how much fan fiction has the man read?) and then destroy it all and thumb his nose at everyone.
Personally, I'd have dropped an atom bomb on the aliens at the start. Or on Torchwood: Cardiff.
ETA: I did not spoiler-cut this because much of the above is pretty general criticism. However there are large spoilers in the comments.